In the next 3 days, Arthas realize the orcs are not the real threat. He should investigate a strange plague in the near village. But he is not alone in this mission. There is Jaina. She is a human wizard hero, with a ranged attack to reach flying units, ant she can cast Blizzard and Summon Water Elemental spells. Heroes with summoning are always cool in Warcraft 3. Heroes are more resilient when exploring alone with no support. Unfortunately, Jaina is not a main hero and will be available for just a couple of missions.